AY Honors/Chemistry/Answer Key
1. Define the following terms:
a. Elements
A class of substances that cannot be separated into simpler substances by chemical means.
b. Compounds
c. Chemical symbols
d. Solutions
e. Atoms
Atoms are basic building blocks of matter. Atoms range in size from .5Å to 24Å. ( Å is the symbol for a unit of measure known as an angstrom. A blond hair is between 170,000 and 500,000Å in diameter and a black hair is between 560,000 and 1,810,000Å in diameter)
We cannot directly see atoms with a regular microscope. The positions of the electron cloud around and atom can be determined using X-ray crystalography, or scanning tunneling microscope. The center of an Atom is "viewed" by using a neutron beam. Light has a wavelength of between 4,000Å and 7,000Å which is like 1000 times the diameter of an atom. Because the wavelength of light is so long it has almost no interaction with the atom.
f. Molecules
g. Periodic table
h. Combustion
i. Acid
j. Salt
l. Neutron
A neutrally charged particle that is a part of the nucleus of an atom. Neutron's have a mass of [math]\displaystyle{ 1.67 \times 10^{-27} }[/math] kg. When we look at water we find that it made up of Hydrogen and Oxygen. Hydrogen has no neutrons, but oxygen has 8 neutrons.
k. Proton
A positively charged particle that is a part of the nucleus of an atom. Protons have a mass of [math]\displaystyle{ 1.67 \times 10^{-27} }[/math] kg. One cubic centimeter of water contains [math]\displaystyle{ 6.02 \times 10^{24} }[/math]protons that form the nucleus of the atoms of hydrogen and oxygen. Hydrogen has one proton at its center and oxygen has 8 protons.
m. Electron
A negativly charged particle with a mass of [math]\displaystyle{ 9.11 \times 10^{-31} }[/math] kg. Electrons form a cloud about the positively chargred nucleus of an atom.
n. Distillation
o. Fractional distillation
p. Filtration
2. What gases extinguish life, and how? Explain the principle of one kind of chemical fire extinguisher.
3. Name two common sources of carbon monoxide. Why is it dangerous?
4. What are the states of matter?
The states of matter are largely defined based on the level of interaction between the molecules and atoms that form the matter. This interaction is temperature dependent, and there are well defined freezing points, melting points, boiling points, condensation points, and ionization energies for each element or molecule.
- Solid
- The atoms are in a fairly rigid structure that at the macroscopic level feals hard or solid. The atoms may be aranged in a very rigid crystaline structure, but there is still vibration within the structure.
- Liquid
- The atoms are free to move around, but do not separate like a gas. Liquids can flow and in general do not feel solid or rigid.
- Gas
- The molecules of a gas are completely free to move around and at standard room temperature they move tens of meters before hitting another molecule, A gas is airy. You will not necessarily know that it is there unless you move through it and feel the wind.
- Plasma
- The molecules of a plasma are ionized, which causes them to repel each other, so a plasma can appear to flow almost like a liquid, and it glows as some of the molecules change ionization states.
In many ways, the modern idea of solid, liquid, gas, and plasma is equivalent to the old alchemy idea of the four elements earth, water, air,and fire.
